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Wednesday, July 26, 2017

SDO will perform Momentum Management (Delta-H) Maneuver #30 today. From 1925-2000 UTC (3:25-4:00 pm ET), SDO science data may be missing or incomplete. These maneuvers are used to manage the reaction wheel speeds on the spacecraft and are a normal part of our operations.

The movie for the lunar transit has been updated. It isn't changed very much, but it's a nice finale to the Great American Eclipse taking place across the United States that day. From 1927-1955 UTC (3:37-3:55 pm ET) on August 21 the Moon will block up to 14% of the Sun.

Thursday, June 15, 2017

I was in Brussels visiting the Royal Observatory Belgium to talk about improving the accuracy of the International Sunspot Number. The ISN is the most important way we have to judge the Sun’s activity. Measurements from over 200 years ago have recently been found in several observatories and we would like to include them in the sunspot number. We are also looking at new ways to combine the data from the many observers who looked at the Sun since 1610. This would make the sunspot number record more accurate and help us understand the solar cycle.

While at ROB I saw how the ISN is measured. The Solar Influences Data Analysis Center (SIDC) at ROB is the World Data Center for the sunspot number and also measures the ISN as often as possible. Under a white dome sits several telescopes designed to look at the Sun. Every clear day an observer walks up the circular staircase to the floor of the observatory.

The long grey telescope projects a large image of the Sun onto a little table behind the telescope with four little spikes. The other telescopes are also used to study the Sun.

The observer secures a piece of paper on the spikes and draw what they see. There isn’t a lot of space and the back of your head can get very warm when it blocks the light of the Sun.

Here is a picture of what the paper looks like on the table. You can see the only sunspot group near the edge of the Sun by the upper right spike. It is quite small but has three spots in the group. (I was in the dome after the drawing for that day was finished and the telescopes are not centered on the Sun.)

Here is a picture of the actual drawing from that day. There is one small spot group with three visible spots. That makes the ISN, which is 10*number of groups + number of spots, 13 for 14-Jun-2017. This may change a little as other stations report, but the decline of Solar Cycle 24 is continuing.

My thanks to the people at the SIDC for both hosting our meeting and giving me at backstage look at the solar observatory. You can get more information, including more drawings and pictures of the Sun, are the SIDC website.

Tuesday, May 2, 2017

May 1, 2017 is SDO's 7th birthday of data collection. We launched on February 11, 2010, reached our final orbit, checked out the instruments and spacecraft, and began returning science data on
My thanks to the SDO Team for their great work on this mission. My congratulations to the SDO Team for winning a NASA Honor Award for Group Achievement! This award reflects the effort and care the SDO Team has put into the mission.
We have updated a few things on the SDO Website. The kiosk movies will be turned off on May 31. Please migrate to the SDO Dashboard at
https://sdo.gsfc.nasa.gov/data/dashboard/,
which has a lot more flexibility in setting up the 48-hour loop movies. As an added attraction, we have added some higher cadence channels (such as the AIA 171 Å channel shown here). This channel has also been produced with a radial gradient filter that enhances the corona around the edge of the Sun.
Update May 3, 2017: Here's an example of how to embed these html5 videos in a website using the high-cadence AIA 171 Å channel.

Today between 1820 and 1845 UTC (2:20-2:45 pm ET) SDO will perform Momentum Management Maneuver #29. This thruster firing is used to keep the speeds of our reaction wheels within safe limits. As the wheel speeds are adjusted by their motors the thrusters fire to keep SDO pointed towards the Sun.

During this maneuver the science data from SDO may be interrupted or contain blurry images.